Surgical instruments having hard jaw surfaces (e.g., made of steel or other hard plastic or composite materials) have been employed in many surgical procedures for retracting, and/or mobilizing tissues or organs, positioning grafts or catheters, and occluding tubular structures, e.g., blood vessels and ducts and other body conduits. Instruments for occluding blood vessels and other body conduits, including jaw-type occlusion instruments, are well-known. In particular, surgical clamps commonly used for occlusion typically include pivoting jaw members that are moveable toward one another and which are actuated by handle members extending from the jaw members. The handle members typically include a ratchet mechanism to hold the engaged clamp in place. Surgical clips are commonly used to occlude smaller blood vessels and other body conduits during surgical procedures. A common type of surgical clip is the parallel jaw clip that includes a pair of jaws oriented generally parallel to one another and moveable from an open to a closed position. Many such clips include compression or extension springs for biasing the jaws together in the closed position. Representative of such clips are those described in, e.g., U.S. Pat. Nos. 3,509,882, 4,931,058, 5,653,720 and 6,267,773. Such clips have gained wide acceptance and are easy to place and remove, and provide for dependable occlusion, and are also useful for other applications, such as suture tags and identification markers.
Many conventional surgical clamps and clips are made of metal, such as stainless steel, hard plastic, or other similarly rigid materials. Such surgical clamps and clips are favored for a number of reasons. They can be manufactured to have a low profile, and the overall structural rigidity of the clamps or clips together with non-deflectable and non-deformable gripping surfaces provides for clamps and clips having good gripping properties. A disadvantage of such clamps and clips is that the hard surfaces and rigidity of the clamps can cause trauma to the clamped vessel at the site of occlusion. Further, in order to improve instrument hold on tissues, such jaws are often manufactured to be variously grooved or serrated. While obtaining superior gripping capabilities, these types of jaw surfaces have been associated with a certain degree of trauma to the gripped tissue.
As a result, a number of atraumatic versions of surgical clamps and clips have been developed for reducing trauma to a vessel during occlusion. In particular, such clamps and clips have been adapted to include jaw surfaces containing cushioned pads, members or inserts. These pads, members or inserts are usually made from easily deformable materials. Due to the increased compliance of these pads, members or inserts, the tractive force applied is often compromised, resulting in undesirable slippage, and in some cases the inserts are prone to slipping off the clamped vessel, especially where the clamps or clips are engaged near the distal ends of their jaws. Also, due to the deformability of such pads, members or inserts, they likewise can be prone to slipping laterally along a clamped vessel, which can further result in a scissoring effect where the jaws twist off-line. In all such situations, effective clamping is compromised.
Methods to improve the tractive force imparted by atraumatic inserts have been attempted, typically by modifying the clamping surfaces of the inserts. For example, FIBRA™ clamp inserts (Applied Medical, Rancho Santa Margarita, Calif.) are covered with a woven layer of flexible, soft, finger-like nylon fibers to help grip vessel adventitia. Similar inserts are disclosed in U.S. Pat. No. 4,821,719 to Fogarty.
U.S. Pat. Nos. 6,099,539; 6,206,896; and 6,387,106 to Howell et al. describe another type of atraumatic insert. These inserts are described as having uniform raised protrusions which interdigitate when the clamp jaws are moved toward one another.
PCT application WO 98/33437 discloses an atraumatic clamping surface with bristles to improve traction. The bristles may be made from polyethylene or nylon and can be provided on the insert in an upright or slanted orientation. When the bristles contact tissue, e.g., a vessel, they crumple in the area immediately adjacent to the vessel. Traction is then provided by the bristles on the sides of the vessel, which block its lateral movement.
PCT Publication WO 99/11179 discloses inserts consisting of a compliant cushion covered with a mesh surface overlay.
U.S. application Ser. No. 10/349,871, filed Jan. 22, 2003, discloses inserts having integrally formed raised patterns that extend from the cushion surface.
Despite the numerous attempts to improve the tractive properties of atraumatic inserts, there remains a need for jaw-type surgical instruments with atraumatic inserts having improved grasping capabilities, including atraumatic inserts that can approach or match the gripping and traction supplied by conventional steel jawed instruments.